A senior Liberal Democrat has risked stoking discontent over Sir Menzies Campbell's leadership by indicating he would stand for the top job "if there was a vacancy".
After a difficult week at the party's conference in Brighton, home affairs spokesman Nick Clegg upped the pressure on Sir Menzies by speaking of his own ambitions.
During an interview at an Observer fringe event, Mr Clegg branded as "rubbish" reports that he had struck a deal 18 months ago to give Sir Menzies a clear run at the leadership in return for his support at a later stage.
He also firmly ruled out running as a candidate against the current leader.
But he added: "If you are asking me, would I throw my hat in the ring if there was vacancy in the future, I probably would."
Tuesday night's comments will reinforce speculation that "rising stars" in the party - such as Mr Clegg and environment spokesman Chris Huhne - are already jockeying to replace Sir Menzies.
Public sniping this week has threatened to overshadow debate on radical policies for tackling climate change, immigration and tax. However, Sir Menzies was boosted on Wednesday by a Guardian/ICM poll which put the party on 20% - up two points from last month.
Mr Clegg also insisted many of the criticisms laid against 66-year-old Sir Menzies were based on "barely disguised ageism".
Sir Menzies' chief of staff, Ed Davey, denied that the remarks were damaging to the leadership.
"We've made very clear there is no vacancy and Ming has made very clear he is leading us into the next election and beyond," he told a briefing for journalists.
